Problem: William starts counting at 43, and he counts by fives. If 43 is the 1st number that William counts. what is the 9th number that he counts?
What is the first number that he counts? $43$ What is the second number that he counts? $\begin{align*}&43 + 5 \\ &= 48\end{align*}$ What is the third number that he counts? $\begin{align*}&43 + 5 + 5 \\ &= 43 + (2 \times 5) \\ &= 53\end{align*}$ What is the 9th number that he counts? $\begin{align*}&43 + (8\times5) \\ &= 43 + 40 \\ &= 83\end{align*}$